Recessed head fastener and driver systems

A threaded fastener having a driver-engageable recess at an end thereof, the recess comprising:

• a central portion;
• a plurality of wings radiating outwardly from the central portion, each of the wings being defined by a pair of sidewalls and an end wall;
• a torque pad formed on at least one wall of each of the wings, the torque pad having a driver-engageable surface and being defined by a relieved region that extends radially inwardly from the torque pad substantially to the central portion of the recess, the driver-engageable surface of the torque pad being located and oriented to define a center of effort that is disposed radially outwardly of the center of effort that would be defined by the entire sidewall in the absence of the torque pad.

A threaded fastener having a driver-engageable recess formed at an end thereof and a ribbed driver for use therewith comprising:

• the recess having a central portion, a plurality of wings radiating outwardly from the central portion, the wings each being defined by a pair of sidewalls and an end wall, that together define a recess envelope, at least some of the sidewalls of the recess having a relieved region defined radially inwardly of its associated end wall to define a relatively raised torque pad between the end wall and the central portion of the recess, the relieved region being defined outside of said envelope;
• the driver comprising a shank portion and a recess-engaging portion formed at the end of the shank portion, the recess-engaging portion comprising a central core and a plurality of blades radiating from the core, each blade having at least one drive wall and an outer wall, at least one rib formed on at least one drive wall of at least one of the blades, the radially outermost end of the at least one rib defining the widest portion of the blade;
• the recess envelope being receptive to the driver, the radially outermost end of the at least one rib and the torque pad being engageable with each other to transmit torque from the at least one rib of the driver to one of said torque pads when the driver and recess are mated.

A threaded fastener having a longitudinal axis and a driver-engageable recess formed at an end of the fastener, the recess comprising:

• a central portion;
• a plurality of wings radiating outwardly from the central portion, the wings each being defined by a pair of sidewalls and an end wall adjoining the sidewalls;
• at least one of the sidewalls having a relieved region defined radially inwardly of its associated end wall to define a relatively raised torque pad between the end wall and the central portion of the recess, the torque pad being an elongate strip and extending longitudinally along a margin of the sidewall that adjoins the end wall, the torque pad having a riser surface oriented along a direction that is disposed at an acute angle to the longitudinal axis of the fastener.